Calcite vs Dolomite

Property Calcite Dolomite
الصيغة الكيميائية CaCO3 CaMg(CO3)2
النظام البلوري Trigonal Trigonal
صنف المعدن 05 Carbonates and Nitrates 05 Carbonates and Nitrates
صلادة موس 3.0 3.5-4.0
اللون Colorless, white, yellow, orange, blue, green Colorless, white, pink, gray, brown
اللمعان Vitreous Vitreous
لون الخط White White
الشفافية Transparent Transparent
الانفصام Perfect rhombohedral {1011} Perfect rhombohedral {1011}
الكسر Conchoidal Subconchoidal

Key Differences

  • Calcite reacts strongly with cold dilute HCl; dolomite only reacts when powdered.
  • Dolomite contains both calcium and magnesium (CaMg(CO3)2); calcite is pure CaCO3.
  • Dolomite crystals often show distinctive curved saddle-shaped (baroque) faces; calcite does not.
  • Calcite has a slightly lower specific gravity (2.71) than dolomite (2.84–2.86).
  • Calcite is trigonal with scalenohedral and rhombohedral habits; dolomite is also trigonal but rarely forms good scalenohedral crystals.

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